Completion and Well-Spacing Optimization for Horizontal Wells in Pad Development

Abstract

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 180956, “Completion and Well-Spacing Optimization for Horizontal Wells in Pad Development in the Vaca Muerta Shale,” by M. Suarez, SPE, YPF, and S. Pichon, SPE, Schlumberger, prepared for the 2016 SPE Argentina Exploration and Production of Unconventional Resources Symposium, Buenos Aires, 1–3 June. The paper has not been peer reviewed. In organic shales, hydraulic fracturing is important for optimizing the production of horizontal wells. For a standalone lateral, the propped surface should be maximized to increase production. In the case of a pad, well spacing is an additional factor. Competition for production between laterals of a given pad should be minimized and is the result of both well spacing and hydraulic-fracture design. A numerical model coupling an explicit description of the hydraulic-fracture geometry and reservoir simulation is proposed to evaluate production interference. Introduction Well Spacing. One of the more critical questions that any asset team must consider concerns well spacing when designing the development plan for a new field. Well spacing defines the total number of wells, the drilling and completion schedule, and the field-production curve. The ultimate decision relies on economic analysis, balancing the expected ultimate recovery against capital and operational expenditures. This work focuses on methods to evaluate different well spacing and on how to reduce the range of uncertainty in the development of the Vaca Muerta play. Well-Spacing Evaluation. Well spacing depends on geomechanics, petrophysics, stimulation design, hydraulic-fracture geometry, and reservoir fluids. These factors are combined by use of numerical simulation to study their effects on the well spacing. The following are some of the methods that are applied to define possible well spacing. Analogs. Using analog methods requires an older field already in development with similar rock and fluid quality, structural complexity, well architecture, and hydraulic-fracture stimulation. The analog approach leads to large uncertainties if any of these parameters are not within the same range or if the older analog field does not have sufficient statistical representation. Simple Reservoir Description Without Explicit Hydraulic-Fracture Description. The first step in simulation is to start with a simple reservoir description in which each property is uniform (porosity, permeability, and fluid saturations). The reservoir model is then coupled with an analytical or numerical production simulator. This kind of approach is appropriate for a field with minimal information. The hydraulic fractures are represented as parallel planes that intersect the wellbore. Hydraulic-fracture properties are kept constant over their whole surface and along the lateral.